Controllable hypoxia-activated chemotherapy as a dual enhancer for synergistic cancer photodynamic immunotherapy

Engineering hypoxia-specific core-shell nanotherapeutics: A sequential strategy for amplified multimodal synergistic breast cancer treatment

The reactive oxygen species (ROS)-based chemodynamic therapy (CDT) and sonodynamic therapy (SDT) have garnered significant interests in advanced tumor treatments. However, their therapeutic efficacy is severely hindered by tumor hypoxia and overexpressed antioxidant glutathione (GSH) in the tumor microenvironment (TME). Motivated by the concept of metal coordination-based nanomedicine, we proposed an innovative strategy for synergistic tumor therapy tailored to the TME. Herein, we developed a multifunctional targeted delivery nanosystem based on the tirapazamine (TPZ)-loaded BT@M/T@T(Cu)GH cascade nanoreactor to enhance the synergistic efficacy of CDT, SDT, chemotherapy (CT) and starvation therapy (ST) against breast cancer. The rationally designed nanoreactor was constructed through covalent conjugation of glucose oxidase (GOx) onto TPZ-loaded BT@M/T@T(Cu) nanoparticles, wherein the formed tannic acid/copper (Ⅱ) (T(Cu)) network served as the "nanovalve"for BT@M/T nanoparticles. Surface functionalization with hyaluronic acid (HA) enabled BT@M/T@T(Cu) nanoparticles to effectively target CD44-overexpressed 4T1 breast tumors via passive targeting and active targeting effect, while mitigating cytotoxicity toward normal cells/tissues. Following successful tumor accumulation, BT@M/T@T(Cu)GH nanoparticles underwent pH-dependent disassembly and released TPZ, Cu2+ and GOx, initiating a cascade of integrated therapeutic functions, including redox balance disruption, starvation, oxidative cytotoxicity, and hypoxia-activated chemotoxicity. When exposed to ultrasound (US) irradiation, BT@M/T@T(Cu)GH nanoparticles demonstrated sonosensitization capability, generating substantial singlet oxygen (1O2) through energy transfer processes. Owing to all these prominent features, the all-in-one nanomedicine exhibited significant apoptotic cell death and noteworthy tumor eradication in vivo, via synergistic combination of GOx-based ST, self-amplified CDT, hypoxia-activated CT, and US-activated SDT. Additionally, the administration of BT@M/T@T(Cu)GH had negligible effects on the normal growth. Taken together, this work establishes a versatile TiO2-based nanosystem integrating tumor targeting and multi-mode synergistic therapy of breast cancer, offering a novel strategy for highly effective and precise treatment of malignancies.

CXCR4/CXCL12 blockade therapy; a new horizon in TNBC therapy

The only subtype of breast cancer (BC) without specific therapy is triple-negative breast cancer (TNBC), which represents 15-20% of incidence cases of BC. TNBC encompasses transformed and nonmalignant cells, including cancer-associated fibroblasts (CAF), endothelial vasculature, and tumor-infiltrating cells. These nonmalignant cells, soluble factors (e.g., cytokines), and the extracellular matrix (ECM) form the tumor microenvironment (TME). The TME is made up of these nonmalignant cells, ECM, and soluble components, including cytokines. Direct cell-to-cell contact and soluble substances like cytokines (e.g., chemokines) may facilitate interaction between cancer cells and the surrounding TME. Through growth-promoting cytokines, TME not only enables the development of cancer but also confers therapy resistance. New treatment targets will probably be suggested by comprehending the processes behind tumor development and progression as well as the functions of chemokines in TNBC. In this light, several investigations have shown the pivotal function of the C-X-C motif chemokine ligand 12 (CXCL12 or SDF-1) axis and chemokine receptor type 4 (CXCR4) in the pathophysiology of TNBC. This review provides an overview of the CXCR4/CXCL12 axis' function in TNBC development, metastasis, angiogenesis, and treatment resistance. A synopsis of current literature on targeting the CXCR4/CXCL12 axis for treating and managing TNBC has also been provided.

Polyphenol-based pH-responsive nanoparticles enhance chemo-immunotherapy in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is challenging to treat due to its difficulty in early diagnosis, highly invasive nature, and high metastatic potential. Currently, the primary treatments for PDAC are chemotherapy and immunotherapy. However, the abundance of extracellular matrix and immunosuppressive cells in the tumor microenvironment (TME) severely impedes the effectiveness of chemotherapy and immunotherapy, promoting tumor growth and metastasis. Indoleamine 2,3-dioxygenase 1 (IDO1), an immunosuppressive tryptophan-metabolizing enzyme, is upregulated in PDAC and degrades tryptophan (Trp) into kynurenine (Kyn), which is toxic to effector T cells and induces regulatory T cells (Treg) recruitment. Herein, we propose a concise strategy to construct a biocompatible, polyphenol-based, pH-responsive nanoparticle to co-deliver docetaxel (DTX) and NLG919 (an IDO1 inhibitor) to significantly enhance chemo-immunotherapy for PDAC by remodeling the TME. The DTX/NLG919-loaded nanoparticles (FPND) effectively elicited immunogenic cell death (ICD) in PDAC cells while limiting immunosuppressive Kyn production through IDO1 inhibition. FPND triggered an effective anti-tumor immune response, characterized by increased CD8+ T cells infiltration and decreased Treg recruitment, leading to significant inhibition of subcutaneous tumor growth in KPC mice through a combination of chemotherapy and immunotherapy. Overall, FPND nanoparticles showed excellent anti-tumor efficacy as a PDAC therapeutic strategy with broad potential in precision medicine.

Cyclooxygenase-2/prostaglandin E2 inhibition remodulated photodynamic therapy-associated immunosuppression for enhanced cancer immunotherapy

Low immunogenicity and immunosuppressive tumor microenvironment (TME) are two pivotal factors restricting tumor immunotherapy. Photodynamic therapy (PDT) directly destroys cancer cells by producing reactive oxygen species (ROS), and enhances the immunogenicity of "cold" tumors by inducing immunogenic cell death (ICD), thereby promoting T cell development against tumors. However, PDT also deteriorates immunosuppression through overactivating the cyclooxygenase-2/prostaglandin E2 (COX-2/PGE2) pathway. To this end, biocompatible albumin nanoassemblies co-delivering IR780 and diclofenac are herein developed for enhanced therapy against triple-negative breast cancer. PDT-exacerbated PGE2 overexpression is effectively abolished by diclofenac-mediated COX-2 inhibition, which reprograms immunosuppressive TME via downregulating the infiltration of various immunosuppressive cells and their cytokine secretion to enhance effector T cell infiltration. Consequently, the enhanced antitumor immunity effectively inhibits tumor growth, prevents the recurrency and metastasis, and remarkably boosts the treatment efficacy of PD-L1 blockade. This study sets an intriguing example for overcoming the COX-2/PGE2 pathway-exacerbated immunosuppression alongside immune activation, thus enhancing synergistic cancer immunotherapy potentiated by various ROS-producing therapies (e.g., PDT and radiotherapy) and chemotherapy.

Injectable Magnetic-Nanozyme Based Thermosensitive Hydrogel for Multimodal DLBCL Therapy

Diffuse large B-cell lymphoma (DLBCL), accounting for 31% of non-Hodgkin lymphomas, remains recalcitrant to conventional therapies due to chemoresistance, metastatic progression, and immunosuppressive microenvironments. We report a novel injectable Fe3O4@DMSA@Pt@PLGA-PEG-PLGA hydrogel system integrating magnetothermal therapy (MHT), chemodynamic therapy (CDT), and immunomodulation. Under alternating magnetic fields (AMF), the system achieves rapid therapeutic hyperthermia (50 °C within 7 min) while activating pH/temperature-dual responsive peroxidase (POD) -like activity in Fe3O4@DMSA@Pt nanoparticles. Catalytic efficiency under tumor-mimetic conditions was significantly higher than Fe3O4@DMSA controls, generating elevated reactive oxygen species (ROS). Flow cytometry revealed 75.9% apoptotic cell death in A20 lymphoma cells at 50 °C, significantly surpassing CDT alone (24.5%). Importantly, this dual mechanism induced immunogenic cell death (ICD) characterized by 4.1-fold CRT externalization, 68% HMGB1 nuclear depletion, and 40.74 nM ATP secretion. This triggered robust dendritic cell maturation (92% CD86+/CD80+ DCs comparable to LPS controls) and T cell activation (16.9% CD25+/CD69+ ratio, 130-fold baseline). Our findings validate the therapeutic potential of magnetothermal-chemodynamic synergy for DLBCL treatment, paving the way for innovative multi-mechanism therapeutic strategies against DLBCL with potential clinical translation prospects.

NIR-II photothermal therapy combined with activatable immunotherapy against the recurrence and metastasis of orthotopic triple-negative breast cancer

It remains a clinical challenge to treat triple-negative breast cancer due to its aggressiveness and metastasis. Photothermal therapy (PTT) in combination with checkpoint blockade immunotherapy offers a promising strategy for such intractable tumors. In this study, a second near-infrared (NIR-II) photothermal agent (PCD NPs) and a tumor microenvironment-activatable nanoprodrug (NLG NPs) for indoleamine 2,3-dioxygenase 1 (IDO-1) blockade have been designed for the therapy of orthotopic triple-negative breast cancer. The NIR-II absorption of PCD NPs can guarantee the high penetration depth of the laser during PTT. At the same time, NLG NPs can be decomposed into the NLG919 monomer in the tumor microenvironment, which can effectively strengthen the immunogenic cell death-induced immune response. NIR-II PTT in synergy with IDO-1 blockade can effectively inhibit tumor growth and prevent tumor recurrence and metastasis. This work thus provides a safe, efficient and feasible method for the treatment of malignant tumors.

Mannose functionalized small molecule nanodrug self-assembled from amphiphilic prodrug connected by disulfide bonds for synergistic cancer chemotherapy and photodynamic/photothermal therapy

Compared to conventional nanocarrier-based drug delivery technology, small-molecule-assembled nanomaterials provide various advantages, including higher drug loading efficiency, lower excipient-related toxicity, and a simpler formulation process. Our research constructed a mannonse-modified small-molecule-assembled nanodrug for synergistic photodynamic/chemotherapy against A549 cancer cells. The hydrophobic hypoxic-activated agent tirapazamine (TPZ) and a hydrophilic fluorescence probe Cyanine 3 (Cy3) constitute this amphiphilic prodrug via a glutathione (GSH)-responsive linkage, which could self-assemble into stable nanoparticles (NPs) and encapsulate a newly synthesized photosensitizer (SeBDP). To enhance the tumor targeting capability, we introduced a tumor-targeted nanodrug SeBDP@TPZ-S-S-Cy/Man NPs by co-assembling mannose-modified lipid (DSPE-PEG-Man). The GSH-responsive linkage of TPZ-S-S-Cy can be rapidly cleaved by GSH to release the therapeutic agents and fluorescent molecule. The released SeBDP generate reactive oxygen species (ROS) to specifically kill cancer cells and elevate hypoxia, thereby enhancing the cytotoxicity of TPZ. SeBDP@TPZ-S-S-Cy/Man NPs exhibited high selectivity and efficiency for in vivo combination therapy without adverse effects to normal tissues. Our findings demonstrate that SeBDP@TPZ-S-S-Cy/Man NPs have great potential for enhancing cancer treatment both in vitro and in vivo by combining an oxygen depletion prodrug with a hypoxia-activated antitumor agent. Thus, the GSH-sensitive self-assembled nanodrug from an amphiphilic hypoxia-activated prodrug, could serve as a potential drug carrier in targeted synergistic cancer therapy.

Overcoming immunotherapy resistance in gastric cancer: insights into mechanisms and emerging strategies

Gastric cancer (GC) remains a leading cause of cancer-related mortality worldwide, with limited treatment options in advanced stages. Immunotherapy, particularly immune checkpoint inhibitors (ICIs) targeting PD1/PD-L1, has emerged as a promising therapeutic approach. However, a significant proportion of patients exhibit primary or acquired resistance, limiting the overall efficacy of immunotherapy. This review provides a comprehensive analysis of the mechanisms underlying immunotherapy resistance in GC, including the role of the tumor immune microenvironment, dynamic PD-L1 expression, compensatory activation of other immune checkpoints, and tumor genomic instability. Furthermore, the review explores GC-specific factors such as molecular subtypes, unique immune evasion mechanisms, and the impact of Helicobacter pylori infection. We also discuss emerging strategies to overcome resistance, including combination therapies, novel immunotherapeutic approaches, and personalized treatment strategies based on tumor genomics and the immune microenvironment. By highlighting these key areas, this review aims to inform future research directions and clinical practice, ultimately improving outcomes for GC patients undergoing immunotherapy.

Orchestrating cancer therapy: Recent advances in nanoplatforms harmonize immunotherapy with multifaceted treatments

Advancements in cancer therapy have increasingly focused on leveraging the synergistic effects of combining immunotherapy with other treatment modalities, facilitated by the use of innovative nanoplatforms. These strategies aim to augment the efficacy of standalone treatments while addressing their inherent limitations. Nanoplatforms enable precise delivery and controlled release of therapeutic agents, which enhances treatment specificity and reduces systemic toxicity. This review highlights the critical role of nanomaterials in enhancing immunotherapy when combined with chemotherapy, radiotherapy, photodynamic therapy, photothermal therapy, and sonodynamic therapy. Additionally, it addresses current challenges, including limited in vivo studies, difficulties in standardizing and scaling production, complexities of combination therapies, lack of comparative analyses, and the need for personalized treatments. Future directions involve refining nanoplatform engineering for improved targeting and minimizing adverse effects, alongside large animal studies to establish the long-term efficacy and safety of these combined therapeutic strategies. These efforts aim to translate laboratory successes into clinically viable treatments, significantly improving therapeutic outcomes and advancing the field of oncology.

Higher Tumor/Organ Accumulation Ratio of Porous Dual Infinite Coordination Polymer Nanocomposites for Efficient Tumor Photothermal-Starvation-Dual Hypoxia Chemo Synergistic Therapy

To enhance tumor comprehensive therapeutic effect of nanomedicines, an efficient strategy that integrates polydopamine and IR780 photothermal therapy, glucose oxidase (GOx) starvation therapy, Banoxantrone (AQ4N) and Tirapazamine (TPZ) dual hypoxia chemotherapy is developed in chronological order. Higher tumor accumulation of porous dual infinite coordination polymer nanocomposites are designed and prepared to implement this strategy, in which fluorescent dye IR780 doped hypoxic prodrugs AQ4N and TPZ coordinated with Cu(II) as the core, this core is encapsulated by GOx-loaded porous polydopamine coordinated with Fe(III) (Fe-MPDA). These nanocomposites exhibit a particle dimension of 118.5 ± 21.7 nm with pore size of 20.1 nm (pore volume 0.012 cm3 g-1 nm-1), facilitating easy accumulation in tumor tissues. Particularly, their ratio of the area under the curve (AUC) of the tumor/organ drug concentration versus time (AUCtumor/AUCorgans) is 1.28. Upon reaching the tumor, the nanocomposites release GOx and Fe-MPDA in initial stage to execute photothermal and starvation therapy, simultaneously enhance the hypoxic level at the tumor site. Then AQ4N and TPZ undergo synergistic chemotherapy in the enhanced hypoxic environment. Animal experiments show a tumor inhibition rate of 100% and a tumor recurrence rate of 0% after 60 d, demonstrating their great potential application for tumor treatment.

An immunotherapeutic hydrogel booster inhibits tumor recurrence and promotes wound healing for postoperative management of melanoma

Low tumor immunogenicity, immunosuppressive tumor microenvironment, and bacterial infections have emerged as significant challenges in postsurgical immunotherapy and skin regeneration for preventing melanoma recurrence. Herein, an immunotherapeutic hydrogel booster (GelMA-CJCNPs) was developed to prevent postoperative tumor recurrence and promote wound healing by incorporating ternary carrier-free nanoparticles (CJCNPs) containing chlorine e6 (Ce6), a BRD4 inhibitor (JQ1), and a glutaminase inhibitor (C968) into methacrylic anhydride-modified gelatin (GelMA) dressings. GelMA-CJCNPs reduced glutathione production by inhibiting glutamine metabolism, thereby preventing the destruction of reactive oxygen species generated by photodynamic therapy, which could amplify oxidative stress to induce severe cell death and enhance immunogenic cell death. In addition, GelMA-CJCNPs reduced M2-type tumor-associated macrophage polarization by blocking glutamine metabolism to reverse the immunosuppressive tumor microenvironment, recruiting more tumor-infiltrating T lymphocytes. GelMA-CJCNPs also downregulated IFN-γ-induced expression of programmed cell death ligand 1 to mitigate acquired immune resistance. Benefiting from the amplified systemic antitumor immunity, GelMA-CJCNPs markedly inhibited the growth of both primary and distant tumors. Moreover, GelMA-CJCNPs demonstrated satisfactory photodynamic antibacterial effects against Staphylococcus aureus infections, thereby promoting postsurgical wound healing. Hence, this immunotherapeutic hydrogel booster, as a facile and effective postoperative adjuvant, possesses a promising potential for inhibiting tumor recurrence and accelerating skin regeneration.

PDL1/HER2-Targeted Lipid-Encapsulated Oxygen Nanobubbles Combined with Photodynamic Therapy for HER2+ Breast Cancer Immunotherapy

Programmed death (PD) 1/PD ligand 1 (PDL1) inhibitors are immune checkpoint inhibitors (ICIs) that may facilitate HER2-positive breast cancer treatment; however, their clinical efficacy remains elusive. Oxygen-enhanced photodynamic therapy (PDT) increases immunogenic cell death (ICD), providing a promising strategy to render the tumor microenvironment more sensitive to the ICIs. Lipid-encapsulated oxygen nanobubbles (Lipo-NBs-O2) obtained using nanobubbles (NBs) water for oxygen delivery in vivo can facilitate enhanced PDT. Here, dual-receptor targeted Lipo-NBs-O2 (DRT@Lipo-NBs-O2) is prepared by modifying Lipo-NBs-O2 with anti-PDL1 scFv and the fusion protein anti-HER2 scFv-tandem-repeat cytochrome c (anti-HER2-nCytc). Copper phthalocyanine is the photosensitizer (PS). DRT@Lipo-PS-NBs-O2 plus near-infrared irradiation leads to robust ICD induction, increasing DC activation and CD8+ T-cell numbers. Modification with anti-PDL1 scFv improves tumor distribution of DRT@Lipo-PS-NBs-O2 and plays the ICI role, invigorating CD8+ T cells and boosting the effects of immunotherapy. Oxygen supplied through DRT@Lipo-PS-NBs-O2 reduces P-glycoprotein expression. Enhanced PDT and Cytc can cause tumor cell death, thereby reducing the immune burden. Under dual receptor targeting and laser local irradiation, tumor cells become subject to the combination effects of PDT, ICD, ICIs, and apoptosis; this effectively suppresses tumor growth and metastasis. Lipo-NBs-O2 affords a combination of oxygen delivery and multidrug therapy to alleviate HER2-positive breast cancer.

Photodynamic therapy with NIR-II probes: review on state-of-the-art tools and strategies

In 2022 10% of the world's population was aged 65+, and by 2100 this segment is expected to hit 25%. These demographic changes place considerable pressure over healthcare systems worldwide, which results in an urgent need for accurate, inexpensive and non-invasive ways to treat cancers, a family of diseases correlated with age. Among the therapeutic tools that gained important attention in this context, photodynamic therapies (PDT), which use photosensitizers to produce cytotoxic substances for selectively destroying tumor cells and tissues under light irradiation, profile as important players for next-generation nanomedicine. However, the development of clinical applications is progressing at slow pace, due to still pending bottlenecks, such as the limited tissue penetration of the excitation light, and insufficient targeting performance of the therapeutic probes to fully avoid damage to normal cells and tissues. The penetration depth of long-wavelength near infrared (NIR) light is significantly higher than that of short-wavelength UV and visible light, and thus NIR light in the second window (NIR-II) is acknowledged as the preferred phototherapeutic means for eliminating deep-seated tumors, given the higher maximum permissible exposure, reduced phototoxicity and low autofluorescence, among others. Upon collective multidisciplinary efforts of experts in materials science, medicine and biology, multifunctional NIR-II inorganic or organic photosensitizers have been widely developed. This review overviews the current state-of-the art on NIR-II-activated photosensitizers and their applications for the treatment of deep tumors. We also place focus on recent efforts that combine NIR-II activated PDT with other complementary therapeutic routes such as photothermal therapy, chemotherapy, immunotherapy, starvation, and gas therapies. Finally, we discuss still pending challenges and problems of PDT and provide a series of perspectives that we find useful for further extending the state-of-the art on NIR-II-triggered PDT.

Recent progress of porphyrin metal-organic frameworks for combined photodynamic therapy and hypoxia-activated chemotherapy

Nanoscale metal-organic frameworks integrated with porphyrins (Por-nMOFs) have emerged as efficient nanoplatforms for photodynamic therapy (PDT), which relies on the conversion of molecular oxygen into cytotoxic singlet oxygen. However, the hypoxic microenvironment within tumors significantly limits the efficacy of PDT. To address this challenge, researchers have explored various strategies to either alter or exploit the hypoxic conditions in tumors. One such strategy involves leveraging the porous structure of Por-nMOFs to load hypoxia-activated prodrugs (HAPs) like tirapazamine (TPZ), thereby utilizing the tumor's intrinsic hypoxic environment to trigger a chemotherapeutic effect that synergizes with PDT. Advances in nanoscience have enabled the development of porphyrin-based nMOFs capable of simultaneously loading both porphyrin photosensitizers and TPZ, ensuring effective release within cancer cells under high-phosphate conditions. The subsequent activation of co-loaded TPZ, by the tumor's own hypoxic microenvironment, and that created during PDT, facilitates a combined PDT and chemotherapy approach. This method not only enhances the suppression of cancer cell proliferation but also improves control over tumor metastasis while mitigating the negative impact of hypoxia on singular Por-nMOFs in PDT. This review summarizes recent advances in Por-nMOFs research, focusing on the design strategies for enhancing water dispersibility, circulatory stability, and targeting specificity through post-synthetic modifications. Additionally, this review highlights the bioapplication of Por-nMOFs by integrating TPZ chemotherapy and other therapeutic modalities to combat hypoxic and metastatic malignancies. We anticipate that this review will inspire further research into Por-nMOFs and advance their application in biomedicine.

Nanomedicines Targeting Tumor Cells or Tumor-Associated Macrophages for Combinatorial Cancer Photodynamic Therapy and Immunotherapy: Strategies and Influencing Factors

Immunotherapy is a promising cancer treatment because of its ability to sustainably enhance the natural immune response. However, the effects of multiple immunotherapies, including ICIs, are limited by resistance to these agents, immune-related adverse events, and a lack of reasonable therapeutic targets available at the right time and place. The tumor microenvironment (TME), which features tumor-associated macrophages (TAMs), plays a significant role in resistance owing to its hypoxic microenvironment and lack of blood vessels, resulting in cancer immune evasion. To enhance immunotherapy, photodynamic therapy (PDT) can increase innate and adaptive immune responses through immunogenic cell death (ICD) and improve the TME. Traditional photosensitizers (PSs) also include novel nanomedicines to precisely target tumor cells or TAMs. Here, we reviewed and summarized current strategies and possible influencing factors for nanomedicines for cancer photoimmunotherapy.

Recent advancements of hydrogels in immunotherapy: Breast cancer treatment

Breast cancer is the most prevalent cancer among women and the leading cause of cancer-related deaths in this population. Recent advances in Immunotherapy, or combined immunotherapy, offering a more targeted and less toxic approach, expand the survival rate of patients more than conventional treatment. Notably, hydrogels, a versatile platform provided promising avenues to combat breast cancer in preclinical studies and extended to clinical practices. With advantages such as the alternation of tumor microenvironment, immunomodulation, targeted delivery of therapeutic agents, and their sustained release at specific sites of interest, hydrogels can potentially be used for the treatment of breast cancer. This review highlights the advantages, mechanisms of action, stimuli-responsiveness properties, and recent advancements of hydrogels for treating breast cancer immunotherapy. Moreover, post-treatment and its clinical translations are discussed in this review. The integration of hydrogels in immunotherapy strategies may pave the way for more effective, personalized, and patient-friendly approaches to combat breast cancer, ultimately contributing to a brighter future for breast cancer patients.

Trend of albumin nanoparticles in oncology: a bibliometric analysis of research progress and prospects

Background

Delivery systems based on albumin nanoparticles (NPs) have recently garnered substantial interest in anti-tumor drug development. However, systematic bibliometric analyses in this field remain lacking. This study aimed to analyze the current research status, hotspots, and frontiers in the application of albumin NPs in the field of oncology from a bibliometric perspective.

Methods

Using the Web of Science Core Collection (WOSCC) as the data source, retrieved articles were analyzed using software, such as VOSviewer 1.6.18 and CiteSpace 6.1.6, and the relevant visualization maps were plotted.

Results

From 1 January 2000, to 15 April 2024, 2,262 institutions from 67 countries/regions published 1,624 articles related to the application of albumin NPs in the field of oncology. The USA was a leader in this field and held a formidable academic reputation. The most productive institution was the Chinese Academy of Sciences. The most productive author was Youn YS, whereas Kratz F was the most frequently co-cited author. The most productive journal was the International Journal of Nanomedicine, whereas the Journal of Controlled Release was the most co-cited journal. Future research hotspots and frontiers included "rapid and convenient synthesis methods predominated by self-assembly," "surface modification," "construction of multifunctional NPs for theranostics," "research on natural active ingredients mainly based on phenolic compounds," "combination therapy," and "clinical applications."

Conclusion

Based on our bibliometric analysis and summary, we obtained an overview of the research on albumin NPs in the field of oncology, identified the most influential countries, institutions, authors, journals, and citations, and discussed the current research hotspots and frontiers in this field. Our study may serve as an important reference for future research in this field.

Glutathione-Responsive Polymersome with Continuous Glutathione Depletion for Enhanced Photodynamic Therapy and Hypoxia-Activated Chemotherapy

The high glutathione (GSH) level of the tumor microenvironment severely affects the efficacy of photodynamic therapy (PDT). The current GSH depletion strategies have difficulty meeting the dual needs of security and efficiency. In this study, we report a photosensitizer Chlorin e6 (Ce6) and hypoxia-activated prodrug tirapazamine (TPZ) coloaded cross-linked multifunctional polymersome (TPZ/Ce6@SSPS) with GSH-triggered continuous GSH depletion for enhanced photodynamic therapy and hypoxia-activated chemotherapy. At tumor sites, the disulfide bonds of TPZ/Ce6@SSPS react with GSH to realize decross-linking for on-demand drug release. Meanwhile, the generated highly reactive quinone methide (QM) can further deplete GSH. This continuous GSH depletion will amplify tumor oxidative stress, enhancing the PDT effect of Ce6. Aggravated tumor hypoxia induced by PDT activates the prodrug TPZ, resulting in an enhanced combination of PDT and hypoxia-activated chemotherapy. Both in vitro and in vivo results demonstrate the efficient GSH depletion and potent antitumor activities by TPZ/Ce6@SSPS. This work provides a strategy for the design of a continuous GSH depletion platform, which holds great promise for enhanced combination tumor therapy.

Clinical application of immunogenic cell death inducers in cancer immunotherapy: turning cold tumors hot

Immunotherapy has emerged as a promising cancer treatment option in recent years. In immune "hot" tumors, characterized by abundant immune cell infiltration, immunotherapy can improve patients' prognosis by activating the function of immune cells. By contrast, immune "cold" tumors are often less sensitive to immunotherapy owing to low immunogenicity of tumor cells, an immune inhibitory tumor microenvironment, and a series of immune-escape mechanisms. Immunogenic cell death (ICD) is a promising cellular process to facilitate the transformation of immune "cold" tumors to immune "hot" tumors by eliciting innate and adaptive immune responses through the release of (or exposure to) damage-related molecular patterns. Accumulating evidence suggests that various traditional therapies can induce ICD, including chemotherapy, targeted therapy, radiotherapy, and photodynamic therapy. In this review, we summarize the biological mechanisms and hallmarks of ICD and introduce some newly discovered and technologically innovative inducers that activate the immune system at the molecular level. Furthermore, we also discuss the clinical applications of combing ICD inducers with cancer immunotherapy. This review will provide valuable insights into the future development of ICD-related combination therapeutics and potential management for "cold" tumors.

Nanoparticles in tumor microenvironment remodeling and cancer immunotherapy

Cancer immunotherapy and vaccine development have significantly improved the fight against cancers. Despite these advancements, challenges remain, particularly in the clinical delivery of immunomodulatory compounds. The tumor microenvironment (TME), comprising macrophages, fibroblasts, and immune cells, plays a crucial role in immune response modulation. Nanoparticles, engineered to reshape the TME, have shown promising results in enhancing immunotherapy by facilitating targeted delivery and immune modulation. These nanoparticles can suppress fibroblast activation, promote M1 macrophage polarization, aid dendritic cell maturation, and encourage T cell infiltration. Biomimetic nanoparticles further enhance immunotherapy by increasing the internalization of immunomodulatory agents in immune cells such as dendritic cells. Moreover, exosomes, whether naturally secreted by cells in the body or bioengineered, have been explored to regulate the TME and immune-related cells to affect cancer immunotherapy. Stimuli-responsive nanocarriers, activated by pH, redox, and light conditions, exhibit the potential to accelerate immunotherapy. The co-application of nanoparticles with immune checkpoint inhibitors is an emerging strategy to boost anti-tumor immunity. With their ability to induce long-term immunity, nanoarchitectures are promising structures in vaccine development. This review underscores the critical role of nanoparticles in overcoming current challenges and driving the advancement of cancer immunotherapy and TME modification.

Introducing urea into tirapazamine derivatives to enhance anticancer therapy

Tirapazamine (TPZ) has been approved for multiple clinical trials relying on its excellent anticancer potential. However, as a typical hypoxia-activated prodrug (HAP), TPZ did not exhibit survival advantages in Phase III clinical trials when used in combination therapy due to the insufficient hypoxia levels in patients' tumors. In this study, to improve the therapeutic effects of TPZ, we first introduced urea to synthesize a series of urea-containing derivatives of TPZ. All urea-containing TPZ derivatives showed increased hypoxic cytotoxicity (9.51-30.85-fold) compared with TPZ, while maintaining hypoxic selectivity. TPZP, one of these derivatives, showed 20-fold higher cytotoxicity than TPZ while maintaining a similar hypoxic cytotoxicity ratio. To highly efficiently deliver TPZP to the tumors and reduce its side effects on healthy tissues, we further prepared TPZP into a nanodrug with fibrin-targeting ability: FT11-TPZP-NPs. CA4-NPs, a vascular disrupting agent, was used to increase the fibrin level within tumors and exacerbate tumor hypoxia. By being combined with CA4-NPs, FT11-TPZP-NPs can accumulate in the hypoxia-aggravated tumors and activate sufficiently to kill tumor cells. After a single-dose treatment, FT11-TPZP-NPs + CA4-NPs showed a high inhibition rate of 98.1% against CT26 tumor models with an initial volume of ∼480 mm3 and four out of six tumors were completely eliminated; it thereby exerted a significant antitumor effect. This study provides a new strategy for improving the therapeutic effect of TPZ and other HAPs in anticancer therapy.

Enhancing photodynamic immunotherapy by reprograming the immunosuppressive tumor microenvironment with hypoxia relief

Tumor hypoxia impairs the generation of reactive oxygen species and the induction of immunogenic cell death (ICD) for photodynamic therapy (PDT), thus impeding its efficacy and the subsequent immunotherapy. In addition, hypoxia plays a critical role in forming immunosuppressive tumor microenvironments (TME) by regulating the infiltration of immunosuppressive tumor-associated macrophages (TAMs) and the expression of programmed death ligand 1 (PD-L1). To simultaneously tackle these issues, a MnO2-containing albumin nanoplatform co-delivering IR780, NLG919, and a paclitaxel (PTX) dimer is designed to boost photodynamic immunotherapy. The MnO2-catalyzed oxygen supply bolsters the efficacy of PDT and PTX-mediated chemotherapy, collectively amplifying the induction of ICD and the expansion of tumor-specific cytotoxic T lymphocytes (CTLs). More importantly, hypoxia releif reshapes the immunosuppressive TME via down-regulating the intratumoral infiltration of M2-type TAMs and the PD-L1 expression of tumor cells to enhance the infiltration and efficacy of CTLs in combination with immune checkpoint blockade (ICB) by NLG919, consequently eradicating primary tumors and almost completely preventing tumor relapse and metastasis. This study sets an example of enhanced immunotherapy for breast cancers through dual ICD induction and simultaneous immunosuppression modulation via both hypoxia relief and ICB, providing a strategy for the treatment of other hypoxic and immunosuppressive cancers.

MOF@COF Nanocapsules Enhance Soft Tissue Sarcoma Treatment: Synergistic Effects of Photodynamic Therapy and PARP Inhibition on Tumor Growth Suppression and Immune Response Activation

Soft tissue sarcomas (STS) are highly malignant tumors with limited treatment options owing to their heterogeneity and resistance to conventional therapies. Photodynamic therapy (PDT) and poly-ADP-ribose polymerase (PARP) inhibitors (PARPi) have shown potential for STS treatment, with PDT being effective for sarcomas located on the extremities and body surface and PARPi targeting defects in homologous recombination repair. To address the limitations of PDT and harness the potential of PARPi, herein, a novel therapeutic approach for STS treatment combining nanocapsules bearing integrated metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), i.e., MOF@COF, with PDT and PARPi is proposed. Nanocapsules are designed, referred to as ZTN@COF@poloxamer, which contain a Zr-based MOF and tetrakis (4-carbethoxyphenyl) porphyrin as a photosensitizer, are coated with a COF to improve the sensitizing properties, and are loaded with niraparib to inhibit DNA repair. Experiments demonstrate that this new nanocapsules treatment significantly inhibits STS growth, promotes tumor cell apoptosis, exhibits high antitumor activity with minimal side effects, activates the immune response of the tumor, and inhibits lung metastasis in vivo. Therefore, MOF@COF nanocapsules combined with PARPi offer a promising approach for STS treatment, with the potential to enhance the efficacy of PDT and prevent tumor recurrence.

Targeting Lysosome for Enhanced Cancer Photodynamic/Photothermal Therapy in a "One Stone Two Birds" Pattern

Highly immunogenic programmed death of tumor cells, such as immunogenic cell death (ICD) and pyroptosis, strengthens antitumor responses and thus represents a promising target for cancer immunotherapy. However, the development of ICD and pyroptosis inducers remains challenging, and their efficiency is typically compromised by self-protective autophagy. Here, we report a potent ICD and pyroptosis-inducing strategy by coupling combined photodynamic/photothermal therapy (PTT/PDT) to biological processes in cancer cells. For this purpose, we rationally synthesize a lysosomal-targeting boron-dipyrromethene dimer (BDPd) with intense NIR absorption/emission, high reactive oxygen species (ROS) yield, and photothermal abilities, which can be self-assembled with Pluronic F127, producing lysosomal-acting nanomicelles (BDPd NPs) to facilitate cancer cell internalization of BDPd and generation of intracellular ROS. Owing to the favorable lysosomal-targeting ability of the morpholine group on BDPd, the intracellular BDPd NPs can accumulate in the lysosome and induce robust lysosomal damage in cancer cells upon 660 nm laser irradiation, which results in the synergetic induction of pyroptosis and ICD via activating NLRP3/GSDMD and caspase-3/GSDME pathways simultaneously. More importantly, PTT/PDT-induced self-protective autophagic degradation was blocked due to the dysfunction of lysosomes. Either intratumorally or intravenously, the injected BDPd NPs could markedly inhibit the growth of established tumor tissues upon laser activation, provoke local and systemic antitumor immune responses, and prolong the survival time in the mouse triple-negative breast cancer model. Collectively, this work represents a promising strategy to boost the therapeutic potential of PTT/PDT by coupling phototherapeutic reagents with the subcellular organelles, creating a "one stone two birds" pattern.

Advances in tumor immunomodulation based on nanodrug delivery systems

Immunotherapy is a therapeutic approach that employs immunological principles and techniques to enhance and amplify the body's immune response, thereby eradicating tumor cells. Immunotherapy has demonstrated effective antitumor effects on a variety of malignant tumors. However, when applied to humans, many immunotherapy drugs fail to target lesions with precision, leading to an array of adverse immune-related reactions that profoundly limit the clinical application of immunotherapy. Nanodrug delivery systems enable the precise delivery of immunotherapeutic drugs to targeted tissues or specific immune cells, enhancing the immune antitumor effect while reducing the number of adverse reactions. A nanodrug delivery system provides a feasible strategy for activating the antitumor immune response by the following mechanisms: 1) increased targeting and uptake of vaccines by DCs, which enhances the efficacy of the immune response; 2) increased tumor cell immunogenicity; 3) regulation of TAMs and other cells by, for example, regulating the polarization of TAMs and interfering with TAN formation, and ECM remodeling by CAFs; and 4) interference with tumor immune escape signaling pathways, namely, the PD-1/PD-L1, FGL1/LAG-3 and IDO signaling pathways. This paper reviews the progress of nanodrug delivery system research with respect to tumor immunotherapy based on tumor immunomodulation over the last few years, discussing the promising future of these delivery systems under this domain.

Recent Advances of Tumor Microenvironment-Responsive Nanomedicines-Energized Combined Phototherapy of Cancers

Photodynamic therapy (PDT) has emerged as a powerful tumor treatment tool due to its advantages including minimal invasiveness, high selectivity and thus dampened side effects. On the other side, the efficacy of PDT is severely frustrated by the limited oxygen level in tumors, thus promoting its combination with other therapies, particularly photothermal therapy (PTT) for bolstered tumor treatment outcomes. Meanwhile, nanomedicines that could respond to various stimuli in the tumor microenvironment (TME) provide tremendous benefits for combined phototherapy with efficient hypoxia relief, tailorable drug release and activation, improved cellular uptake and intratumoral penetration of nanocarriers, etc. In this review, we will introduce the merits of combining PTT with PDT, summarize the recent important progress of combined phototherapies and their combinations with the dominant tumor treatment regimen, chemotherapy based on smart nanomedicines sensitive to various TME stimuli with a focus on their sophisticated designs, and discuss the challenges and future developments of nanomedicine-mediated combined phototherapies.